1 /* 2 * Generic Syscon Poweroff Driver 3 * 4 * Copyright (c) 2015, National Instruments Corp. 5 * Author: Moritz Fischer <moritz.fischer@ettus.com> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; either version 2 of 10 * the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 */ 17 18 #include <linux/kallsyms.h> 19 #include <linux/delay.h> 20 #include <linux/io.h> 21 #include <linux/notifier.h> 22 #include <linux/mfd/syscon.h> 23 #include <linux/of_address.h> 24 #include <linux/of_device.h> 25 #include <linux/platform_device.h> 26 #include <linux/pm.h> 27 #include <linux/regmap.h> 28 29 static struct regmap *map; 30 static u32 offset; 31 static u32 mask; 32 33 void syscon_poweroff(void) 34 { 35 /* Issue the poweroff */ 36 regmap_write(map, offset, mask); 37 38 mdelay(1000); 39 40 pr_emerg("Unable to poweroff system\n"); 41 } 42 43 static int syscon_poweroff_probe(struct platform_device *pdev) 44 { 45 char symname[KSYM_NAME_LEN]; 46 47 map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap"); 48 if (IS_ERR(map)) { 49 dev_err(&pdev->dev, "unable to get syscon"); 50 return PTR_ERR(map); 51 } 52 53 if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) { 54 dev_err(&pdev->dev, "unable to read 'offset'"); 55 return -EINVAL; 56 } 57 58 if (of_property_read_u32(pdev->dev.of_node, "mask", &mask)) { 59 dev_err(&pdev->dev, "unable to read 'mask'"); 60 return -EINVAL; 61 } 62 63 if (pm_power_off) { 64 lookup_symbol_name((ulong)pm_power_off, symname); 65 dev_err(&pdev->dev, 66 "pm_power_off already claimed %p %s", 67 pm_power_off, symname); 68 return -EBUSY; 69 } 70 71 pm_power_off = syscon_poweroff; 72 73 return 0; 74 } 75 76 static int syscon_poweroff_remove(struct platform_device *pdev) 77 { 78 if (pm_power_off == syscon_poweroff) 79 pm_power_off = NULL; 80 81 return 0; 82 } 83 84 static const struct of_device_id syscon_poweroff_of_match[] = { 85 { .compatible = "syscon-poweroff" }, 86 {} 87 }; 88 89 static struct platform_driver syscon_poweroff_driver = { 90 .probe = syscon_poweroff_probe, 91 .remove = syscon_poweroff_remove, 92 .driver = { 93 .name = "syscon-poweroff", 94 .of_match_table = syscon_poweroff_of_match, 95 }, 96 }; 97 98 static int __init syscon_poweroff_register(void) 99 { 100 return platform_driver_register(&syscon_poweroff_driver); 101 } 102 device_initcall(syscon_poweroff_register); 103